There are many things you can do within the CBD of Brisbane.
Things to Do:
Visit the new Central Library which has a great children's section
Roma Street Parklands has lovely flowers and a great playground
Visit the Museum of Brisbane
Go up in the tower of the Town Hall
Visit Brisbane's oldest building The Windmill
Climb Jacob's Ladder
Look at the Plaques for the Brisbane Literary Trail in Albert st
CBD parks- Anzac Square,Post Office Square, Brisbane Square,King George Square,Victoria Square.
Catch a Train,bus or a citycat to the City
Hats and sunscreen
The Cathedrals of Brisbane are beautiful!
Brisbane Arcade off Queen st is an amazing old style arcade
The Brisbane Botanic Gardens
The Commissariat Museum